Telephone system



June 5, 1945. Q s. RHOADS 2,377,453

TELEPHONE SYSTEM Filed March 11, 1944 2 Sheets-Sheet l Calzeal PartyCommunity DaL Office,

INVENTOR asizhmwas Cal Z in Eal'ty ATTORNEY June 5, 1945. Q s RHOADS 2,3

TELEPHONE SYSTEM Filed March ll, 1944 2 Sheets-Sheet 2 INVENTOR BSRhaads M M ATTORNEY ?aienied June 5, 1945 UN TE STATES PATEN .iO F

[7 claims.

This invention relates to telephone, systems and, more particularly, tostep-by-step telephone systems. This invention also relates to arrangements for determining whether or not a subscribers line is busy or outof order. This invention also relates to. arrangements for enabling atelephone operator either to override a line appearingto be busy so thatshe maydetermine whether the line actually is busy or out of order, orto monitor the busy line, or, ii desired, to converse with the partiesto the telephone conversation on the busy line According to presenttelephone ,practices a manual ofllce-which may be located, for example,in acity and may be attended by one .or more telephone operators-maybeconnected to a community dial oillcewhich' is a much smaller oflicelocated'in an outlying village or hamlet and is generally junattendedh-A subscriber in the communitydial ofiice area may be connected toanother subscriber in the area of the community dial 'oiilce in awell-known manner as,-for example, by dialing the latter party in theusual way. During the conversation between the two parties or at anytime when the line to the subscriber of the community dial oilice is outof order, as occurs, for example, when the latters receiver is off thehook, it is practically impossible for the operator at the manual ofliceto determine whether the subscribers line actually is busy or out oforder. Such information would be of value to the operator at the manualoflice for she may have another call awaiting connection to the calledparty and may, therefore, have considerable telephone equipment tied upwhile waiting for the busy line to become idle. If she were able todetermine definitely that the line is out of order,

she could then release the telephone equipment for other purposes.Moreover, the operator might have an urgent call that must be made tothe called party and in that event it would be of value to have anarrangement to enable the operator to override the busy circuitand-connect her own telephone set to the called partys line to conversewith that party.

Accordingly, it is one of the objects of this invention to provide asimple and inexpensive arrangement for enabling an operator at, forexample, a manual telephone ofiice, to seize a subscribers lineextending, for example, from a community dial oflice, to monitor theline while it is busy, or to converse with the parties engaged in theconversation. Such an arrangement will also serve to apprise theoperator (and 7 others) as to whether or not the subscriber's line isout of order.

In one of the arrangements to be described hereinafter, a subscriber ina community dial oflice area will be shown connected to anothersubscriber in the community dial ofllce area, and

the arrangement will include means whereby the operator may verify thebusy condition on the already established connection. While theconversation between the parties continues the operator may manipulate aswitch, for example, and then dial an additional digit over the line tothe called party to connect her own telephone set to the called partysline. The "overriding circuit is completed without in any wayinteriering with or otherwise ailecting the conversation over the busyline.

It is, therefore, another object of this invention to providearrangements for enabling an operator to dial a community dial oiiicesubscriber whose line is connected to another line and finds it busy andthen, while holding the train of equipment she has established to thebusy line, to permit the operator to complete her own connection to thebusy line by dialing another digit, so that the operator may thenmonitor the circuit or converse with the parties to the conversation.

These and other objects of this invention will be better understood fromthe more detailed description hereinafter following when read inconnection with the accompanying drawings in a which Figures 1 and 2,when placed adjacent to each other with Fig. 1 above Fig. 2, willillustrate one embodiment of the invention in which a single conductorextending between the master oilice and the community dial oiiice mayserve to control an overriding circuit for a busy line.

Referring to Figs. '1 and 2, there is shown a manual oflice MO connectedto a community dial ofllce CDO at which there may be a plurality ofconnector circuits only two of which are shown, and are designated CONand CONz. The arrangements of Figs. 1 and 2 will now be described withreference to the connection of a calling partys telephone set, such asTS1, which may be in the area of a community dial oillce CDO, to acalled partys telephone set, such as TSz, which may also be in the areaof the community dial flice CDO.

When the calling party TS1 removes his receiver from its switchhook theapparatus at the community dial oflice CDO, generally designated CDE,will act in a well-known manner to seize one of the various connectorssuch as, for example, CON1 at the community dial ofilce CDO. Apparatussuitable tor this purpose is shown and described in the patent to E. D.Butz, No. 2,021,286, dated November 19, 1935. Immediately after theconnector CON1 is seized, the relay A will become operated over acircuit which includes the upper winding of relay A, and ground; The

operation of relay A will complete an obvious circuit for operatingrelay B. The operation of relay B will cause ground to be applied to thesleeve conductor 8, which extends to the line finder-selector of theequipment MOE in a wellknown manner, the grounding circuit extendingfrom ground at the armature T: of relay B and its make contact,conductor 2|, to the sleeve terminal S. This ground applied to thesleeve conductor will guard the connector CON1 from seizure by any otherseelctor and hold the preceding selectors and line finder in thecommunity dial ofiice CDO. The operation of relay B will open theoperating circuit of the release magnet RIB which controls; the releaseof all of the equipment at the. connector CONi, the release magnet RLS'having previously been connected to theback contact or armature T1 ofrelay B through conductor and the back contact'oi armature Ls ofrelay-K. The relay B also prepares a circuit for operating the verticalmagnet VM as will now be described. 7

After the calling party's telephone set T51 has been connected to theconnector (BN1 at the community dial omce CDO by dialing a digit (ordigits), thenext digit dialed by the calling party's telephone set T81will provide a train of pulses for releasing and reoperating' relay A,relay A being operated and released once for each oi the various pulsesof the digit dialed by the calling party. The vertical magnet VM isconnected to the back contact or the armature of relay A over a circuitwhich includes battery, the winding of the vertical magnet VM, thearmature T: and

back contact of relay H, contacts 21 and 22 of the oil-normal switchVON, conductor 28, the

make contact associated with armature T1 of relay B to the back contactof the armature of relay A which is grounded. The vertical magnet W isconnected in parallel to the winding 0! the relay C over a circuitincluding conductor 22, the back contact and armature L1 of relay K andconductor 3|. The parallel arrangement of the vertical magnet VM andrelay C will cause both of those devices to be operated simultaneously.However, relay C as well as relay B are of the slow-release type andhence, they will be held in their operated positions during the pulsingof the first digit. The vertical magnet VM, however, will step its shaft(not shown) in a vertical direction through a number of steps whichcorrespond to the digit dialed.

As soon as the shaft or the vertical ma net W has moved up one verticalstep, the ofl-normal switch VON will be moved to its operated position.However, the circuit to the vertical magnet VM will now be completedthrough the back contact and armatureTa of relay H. conductor 2!, theback contact and armature L1 oi! relay K, conductor 20, conductor 22,conductor 22,

the make contact and armature T1 of relay C,

will now be described.

In response to the next set of pulses corresponding to the third (ornext) digit dialed by the calling party's set T81 after connector C081is seized, the relay A will again release and reoperate once for each ofthe pulses transmitted as in the case of the previous dial pulsesreceived. This will cause the rotary magnet RJOT1 and the relay E to beoperated in series over a circuit which includes battery, the rotarymagnet ROTi, the winding of relay E, the back contact and armature T4 ofrelay H, conductor I8, the back contact and armature T: of relay C,conductor 2|, contacts ll and 20 of switch VON, cond It, the makecontact and armature T1 of relay B, the back contact and armature oirelay A, and ground. The subsequent pulses of the third (or next) digitwill step the shaft of the rotary magnet ROT1 in a rotary direction in awellknown manner. The relays B and E, however, will remain operatedduring these received pulses because these relays are 0! theslow-release type. The relay E when operated holds open the path to thevertical magnet VM, the path to the vertical magnet VM being operated atthe back contact of the armature T: oi the relay E. Relay E alsocompletes a path for operating relay H, the operating circuit includingbattery, the winding of relay H, the armature T: of relay E and its makecontact, conductor ll, the armature T4 of relay B and its make contact,and ground. The relay H is then locked in its operated position throughthe make contact of its own upper armature T1 and hence relay H is heldoperated even after relay E releases. The opening of the back contact ofarmature Ts of relay H will open the operating circuit to the releasemagnet BRLB.

The relay H also opens the operating path for relay E at the backcontact of the armature T4 of relay H. Moreover, the operation oi relayH completes apath to-the rotaryselector magnet HOT: at the make contactof armature T; of relay H, this path being connected in parallel withthe winding of relay C by conductor 22, the armature L1 of relay K andits back contact, and conductor ll.

As soon as relay E releases, it provides a path for operating relay C inparallel with the selector rotary magnet ROT: upon the subsequentrelease of relay A. This circuit may be traced from battery andthewinding of relay C, conductor 22, the armature T 0! relay G and its backcontact, the armature T: of relay E and its back contact, the makecontact and armature T: of relay H, conductor 24, contacts 35 and 28 ofswitch VON, conductor 3, the make contact 01' armature T1 of relay B,the back contact of the armature of relay A, and then to ground. Duringthe next series of pulses, relay C operates along with the rotarystepping magnet ROT: to control relay G which serves to test the calledparty's line to determine whether'or not it is busy, as will now bedescribed.

Upon the operation of relay C and magnet ROTz in response to thereception of the pulses of the fourth (or next) dialed digit, a circuitwill be completed'irom the winding oi relay 0 to the sleeve terminal 8extending to the called partys line. This circuit may be traced frombattery, the winding of relay G, the make con tact and armature T3 ofrelay C, contacts 42 and 43 of the switch RON, conductor 44, to thesleeve terminal S. Switch RON is, of course, controlled by rotary magnetROTz. If ground is found on the latter sleeve terminal S at any timeduring the pulsing of the fourth (or next) digit, the relay G willbecome operated. Relay C is of the slow-release type and will remainoperated during the remaining pulses of the digit. During this periodrelay G tests the called lines sleeve terminal S. Should battery beconnected to the sleeve terminal S, the relay G will remain unoperated,thereby indicating an idle line condition. Upon the operation of relay Gdue to the presence of ground on the sleeve terminal S, a source of busytone will be connected through the make contact and armature T4 of relayG to the calling partys set TSi, the busy tone being transmitted to theset TS1 over the ring conductor R and returned over the tip conductor T.Should relay G become operated, it will open the operating path to relayC at the back contact of the armature T1 of relay G. Once relay Gbecomes operated it will remain operated until the connector CONl isreleased by reason of the calling party hanging up.

If the called partys line is idle the relay G remains unoperated. Duringthe received pulses of the fourth (or next) digit, rotary magnet ROTzwill be stepped once in accordance with each of these pulses. The rotarymagnet ROT: may serve to select any one of a number of codes in awell-known manner for ringing the called partys line, but only oneringing current will be referred to hereinafter for ringing the calledpartys line. At the end of the received pulses of this digit, relay Cwill release.

If the called partys line is idle the relay K will become operated overa circuit which includes the ground at the sleeve terminal S, conductor44, contacts 43 and 42 of the switch RON, the armature T3 and backcontact of relay C, the upper winding of relay K, the armature T: andback contact of relay G, the armature T: and make contact of relay B,and ground. The operation of relay K will connect ground through itsarmature T and its make contact and through conductor 44 to the sleeveterminal S to guard the called partys line against seizure by otherconnectors such as CONz. The relay K becomes locked in its operatedposition over a circuit which includes battery, the lower winding ofrelay K, the armature L1 and make contact of relay K, conductor 46,conductor 40, the armature T4 of relay B and its make contact, andground. The relay K will lock the connector CON! in its operatedposition by opening the circuit to its release magnet RLS at the backcontact of its armature L3 and the connector CON1 will remain lockeduntil the relay K becomes released. The relay K will connect the calledpartys telephone line to its own armatures T2 and L1 and in turn to thearmatures T5 and T2 of relay F so that the called party's line maybecome connected to the calling partys line immediately after relay Fbecomes operated.

The operation of relay K will close a circuit for operating relay J overa path which includes battery, the winding of relay J, conductor 41, thearmature T4 and back contact of relay F, conductor 48, themake-before-break contact of armature T1 of relay J, conductor 49, thearmature T4 of relay K and its make contact, and

round at GP which is completed through a contact PU on a ringing machine(not shown). The relay K connects battery 15 to the called line over acircuit including the back contact and armature T: of relay J, conductor55, back contact and armature T5 of relay F, conductor 82, armature T:of relay K and its make contact, conductor 53, and over conductor R tothe called subscribers set T32. then back over conductor T, over themake contact and armature L1 of relay K, conductor 52, armature T2 ofrelay F and its back contact, conductor II, armature T4 of relay J andits back contact, conductor 13, the lower winding of relay F, to groundat GD. This circuit applies pre-trip battery to the called line to causeconnector CON1 to cut through and allow the parties to converseimmediately if the called party removes his receiver before his bellrings. The operation of relay J will cause ring! ing current to besupplied from the ringing generator RG to the called partys line over acircuit which includes the ringing generator RG, conductor I0, thearmature Ta and its make contact, conductor ii, the armature T2 of relayF and its back contact, conductor 52, the armature La of relay K and itsmake contact, over the tip conductor T to the called partys set T82,then back over the ring conductor R. conductor 53, the armature T: ofrelay K and its make contact, conductor 82, the armature T5 of relay Fand its back contact, conductor 55, the armature T: of relay J and itsmake contact to the ringing ground GD. This ringing current may betransmltted to the called party until the call is an swered.

When the called party answers in response to the ringing signal thereceiver of the called party's set TS: will be removed from itsswitchhook, thereby causing relay F to become operated. The operatingcircuit for relay F will include ground at GD, the lower winding ofrelay F, conductor 14, the make contact and armature T: of relay J,conductor BI, the back contact and armature T5 of relay -F, conductor82, armature T2 of relay K and its make contact, conductor 53, conductorR, set TSz, conductor T, the make contact and armature L2 of relay K,conductor 52, armature T2 of relay F and its back contact, the makecontact and armature T: of relay J, the ringing apparatus RB, the lowerwinding of transformer TR1, battery and ground. The operation of relay Fwill cause this relay to become locked, the locking circuit includingbattery, the upper winding of relay F, the make contact and armature Tlof relay F, conductor 58, make contact and armature T4 of relay B, andground. The relay F will then connect the calling partys set TS! to thearmatures T5 and T: of relay F which were previously traced to thecalled partys set TS: upon the operation of relay F.

The operation of relay F will also connect talking battery to tipconductor T of the line extending to the called party's set. The twoparties may then converse with each other. This battery will be suppliedthrough the lower winding of relay D, conductor 58, conductor 59, themake contact and armature T2 of relay F, conductor 52, the armature L2of relay K and its make contact over the tip conductor T to the calledpartys set TSz. Ground will simultaneously be supplied to the ringconductor R extending to the called party's set over a circuit whichincludes the upper winding of relay D, conductor 80, conductor 6|, thearmature T5 of relay'F and its make contact, conductor 82, the armatureT: 01'

relay K and its make contact, and the ring conductor R which extends tothe called partys set TSz. The connection of battery and ground to thecalled partys set will operate relay D which in turn will release therelay J. The relay D will also reverse the application of battery andground to the calling partys set TSi so that ground will now be appliedfrom the upper winding of relay A to the ring conductor R extending tothe calling party's set T81, and battery will be connected from thelower winding of relay A to the tip conductor T of the calling partysset TSi.

It has been shown hereinabove that dial pulses corresponding to thecalled station TS: and emanating from the calling partys station TSi mayoperate the connector CONi at the community dial ofllce CDO forinterconnecting the two stations so that the parties may converse witheach other. Should another party (not shown) seek to reach the samecalled party T52, the additional partys telephone set will be connectedto another one of the connectors such as CONz at the community dialoflice CDO. However, the sleeve SS will then be grounded due to the busycondition of the called line and the additional party will not obtainaccess to the line of the called party. In that case the relay GG ofFig. 2 will be operated over a circuit which includes battery, thewinding of relay GG, the armature T3 and make contact of previouslyoperated relay CC, the contacts 42 and 43 of the switch RON: and groundat the sleeve terminal SS. It will be observed that the circuit of Fig.2 is the same as that of Fig. 1 so far as the connector CON: isconcerned but only the essential parts of the connector CON: have beenshown to explain the features of the overriding circuit of thisinvention.

The operator at the manual oilice MO may connect -her telephone set TS:across the tip and ring conductors TI and RR to determine hether or notthe called partys line is busy or out of order, or for other purposes.This may be done by the operator inserting a calling cord in a trunkjack, and dialing the called partys number in a well-known manner. Theoperator will also insert a dialing cord (not shown) in the dial jackafter she hears dial tone in the trunk. The operator then will dial thedesired number and then she removes the dialing cord from the dial jack,after which she can again listen on the trunk. The operator will thenactuate her key KY if the line tests busy and this will complete anobvious circuit to a master control relay MC located at the communitydial ofllce CDO. The master control relay MC has a pair of contactsextending to each of the various connectors such as CONi, CON2, etc.,for simultaneously actuating certain relay circuits of these connectorsso that the operator's telephone set TS: will be bridged across thecalled partys line that appears to be busy. While holding theconnection, the operator will then dial another digit (any digitwhatever) to complete the overriding circuit while key KY0 is heldoperated. This will now be explained.

In response to the dialing of a number corresponding to the calledpartys line by the operators set TSa-WhiCh is now connected to theconnector CONa-the relay GG will become operated over the circuit which,as already noted, includes battery, the winding of relay GG, thearmature T3 of relay CC and its make contact, contacts 42 and 43 ofswitch RONz and the sleeve terminal SS which is grounded because thecalled partys line is busy. As the master control relay MC becomesthereafter operated in response to the operator's closure of the keyKY0, and as the operator dials another digit, the relay AA will becomereleased so as to ground its armature. This will cause relay K to becomeoperated. The circuit for operating relay KK will include battery, itslower winding, conductor 10, the armature T3 of relay MC and its makecontact, conductor II, the armature T: of relay GG and its make contact,conductor 12, the back contact and armature of relay AA, and ground. Theoperation of the relay KK will then connect the tip and ring conductorsTT and RR of the called partys line to the armatures T: and T5 of relayFF through the armatures La and T: of relay KK and their make contacts,respectively. The operation of relay KK will then cause relay FF tobecome operated over a circuit which includes the ground at GD, thelower winding of relay FF, the back contact and armature T4 of relay JJ,armature T2 of relay FF and its back contact, armature L2 of relay KKand its make contact, conductor T1, the calling partys set TSz,conductor RR, the armature T2 of relay K and its make contact, thearmature T5 of relay FF and its back contact, the armature T2 of relayJJ and its back contact, resistor Z, battery and ground. Relay FF willbe locked as already described with regard to connector CON1. Inresponse to the operation of relay FF the circuit to the called partysset TSz will now be extended to the operators set TS; through thearmatures T: and T5 of relay FF and their make contacts. The operatorsset T53 will now be connected to the telephone circuit previouslyestablished by connector CON1. The operator may then determine whetheror not the called partys line is busy or out of order due to the removalof the receiver from its hook. Thus the busy line may be seized and itscondition tested by the operator first dialing the number correspondingto the called party's station, then operating key KY0, and then dialinganother digit to complete the connection to the busy line.

It will be observed that the master control relay MC includes aplurality of armatures each of which is assigned to but one of thevarious connectors and, as there would be several connectors in anordinary community dial oflice, the relay MC would require as manyarmatures as there are such connectors in the ofllce. The operation ofthe master control relay MC in response to the manipulation of the keyKY0, however, will permit the operation only of the relay such as K ofconnector CONz, which receives an additional or fifth digit dialed bythe operator for the purpose of overriding a busy condition. Thus, theonly subscriber's line seized will be the one which responds to thegroups of dial pulses emanating from the operators telephone set TSz.The last of these dial pulses will operate a relay such as FF ofconnector CONz, for example, to complete a path to the busy partys line.Thus the operator will be bridged across the telephone line of theparticular party that is dialed by the operator and the connection willbe completed only when the operator actuates her key KY0 and dials anadditional digit.

While this invention has been shown as applied to a step-by-steptelephone system having an additional conductor interposed between thecommunity dial oflice CD0 and the manual ofllce M0 for actuating themaster control relay MC, similar operation of the master control relaymay be effected over a loop dial trunk, or over a composite trunk dialleg, or by other means, as will be apparent to those skilled in the art.

While this invention has been shown and described in certain particularembodiments merely for the purpose of illustration, it will beunderstood that the general principles of this invention may be appliedto other and widely varied organizations without departing from thespirit of the invention and the scope of the appended claims.

What is claimed is:

1. In a telephone system, the combination of a telephone lineinterconnecting two telephone stations, and means to monitor over saidtelephone line, said means including means responsive to dial pulsescorresponding to one of said interconnected telephone stations and to anadditional dial pulse to seize the busy telephone line withoutinterfering with communication over said telephone line, the busytelephone line being seized for communication thereover only after saidadditional digit is dialed.

2. In a telephone system, the combination of a telephone line, a firstsubscriber's set connected to said line, a second subscriber's set,means responsive to predetermined dial pulses to connect said telephoneline to said second subscriber's set, an operators set, and meansresponsive to predetermined dial pulses transmitted from said operator'sset and to an additional pulse to connect said operators set to saidsecond subscriber's set, the second subscriber's set being seized forcommunication therewith only after said additional pulse has beentransmitted.

3. In a telephone system, the combination 01 a first telephone set, asecond telephone set, a line, means responsive to predetermined dialpulses produced by said first telephone set to connect said firsttelephone set to the second telephone set over said line, an operatorsset, and means to connect said operators set to said line to determinewhether said line is busy, said latter means including means responsiveto additional pulses corresponding to said predetermined dial pulses andto an additional pulse to seize said line, said line being seized forcommunication thereover only after said additional pulse has beentransmitted.

4. In a telephone system, the combination of a plurality of connectorseach of which may serve to connect a pair or telephone stations to eachother, a calling telephone station, a called telephone station, a thirdtelephone station, means responsive to predetermined dial pulsesemanating from the calling station and corresponding to the calledstation to connect said calling station to said called station throughone of said connectors, means responsive to the same dial pulsesemanating from the third telephone station and corresponding to thecalled station to return a busy signal to the third station over anotherof said connectors, and means responsive to an additional dial pulse ofthe series of dial pulses transmitted to the latter connector to seizethe circuit interconnecting the calling and called stations formonitoring said circuit.

5. In a telephone system, the combination of an attended office, anunattended office, a subscribers circuit connected to said unattendedoffice, means to dial said subscriberscircuit from the attendedofliceand to determine whether said subscriber's circuit is busy, andmeansto dial an additional digit when said subscriber's circuit testsbusy to seize said subscriber's circuit without interfering withwhatever conversation may be going on over said subscriber's circuit,said busy subscriber's circuit being seized for conversation thereoveronly after the additional digit has been dialed.

6. In a telephone system, the combination of an attended oflice havingan operators set, an unattended oflice, a subscriber's circuit connectedto said unattended oflice, means to monitor the subscribers circuit fromthe attended office, said means including means responsive to dialpulses corresponding to said subscriber's circuit to return a busysignal to the operators set at said attended oflice, and meansresponsive to additional dial pulses to connect said operators set tosaid subscriber's circuit for communication purposes without interferingwith any conversation over said subscriber's circuit.

'7. In a telephone system, the combination of an unattended telephoneoiiflce, two subscriber's telephone sets connected to each other throughsaid unattended ofllce, an attended telephone office connected to saidunattended ofllce, an operators telephone set at said attended oflicehaving means for producing dialing pulses for signaling one of saidsubscriber's sets, equipment at said unattended ofllce which may beoperated by said dialing pulses, a circuit interconnecting saidunattended ofllce with said attended ofllce, means controlled at saidattended ofllce to operate said sets.

CHARLES STANLEY RHOADS.

